In fossil fuel burners it is well known that the addition of water vapor enhances the combustion efficiency. Introduction of water vapor may be solely by positive pressure, U.S. Pat. No. 3,724,429; negative pressure (vacuum), U.S. Pat. No. 3,107,657; or both positive and negative pressure, U.S. Pat. No. 3,862,819. In this last-mentioned patent, the concept of water vapor introduced into a combustion chamber is applied to central heating units, such as oil heaters. This patent provides a fuel catalyzer which has a first conduit from the high pressure side of the fan associated with the oil burner to a position below a reservoir of water. A second conduit transports water vapor to the downstream side of the fan from a chamber above the reservoir.
My invention disclosed in U.S. Pat. No. 4,009,984 comprised a vacuum-tight housing, a reservoir of water in the housing, and a constant vapor chamber disposed above the reservoir. A vacuum was created in the vapor chamber, which resulted in an airflow being drawn into the housing and through the reservoir. The airflow entrained metered amounts of highly vaporized water molecules which flowed into the vapor chamber and ultimately into the combustion chamber.
In Ser. No. 771,718 an apparatus and method are provided wherein the size of the vapor chamber may be varied and uniform flow of air through the reservoir and into the vacuum chamber is achieved.
In that invention a tube is adjustably secured to and depending from a free floating platform. The platform floats on a reservoir of water. The tube extends into the water and is characterized by a plurality of perforations. The perforations are immersed in the reservoir. Flow passages are formed externally of the tube whereby air is drawn through the flow passages, the water and ultimately into the vacuum chamber as a vapor stream.
Further work in this area has indicated that of the dual concept employed, namely the constant vapor chamber and constant dimensions of the tube within the reservoir, the latter appears to be more important.
The present invention comprises a housing having a reservoir of water therein. A depending tube is structured to provide a uniform flow of air, the tube preferably having a plurality of slots in the lower portion thereof. The tube is secured to a free-floating platform, the upper portion of the tube communicates directly with the ambient. The vapor chamber is formed above the reservoir and is defined by the surface of the reservoir and the inner surface of the upper portion of the housing.